Transporting commodities by common rail carrier is one of the most economical and efficient means to move commodities to destination points across North America. Most railcars transport a certain volume or weight of commodity which determines the commercial value of materials being shipped. Most railcars are loaded to capacity of the railcar by either volume or weight. In either case, the weight of the commodity is essential to determine the value of commodity being transported.
There are several prior art devices that can detect and communicate to a user if a railcar is either empty or loaded. These devices are basically position devices that determine the compression of a railcar truck suspension spring. Such a device indicates whether the suspension spring is fully compressed (loaded car) or fully relaxed (empty car). This method does not measure the specific weight of the railcar, but rather the status: either empty or loaded. Furthermore, such devices are not suitable for transmission of the load information to a remote location.
Prior art weighing devices also are typically unable to withstand the rigors of the railcar environment. Therefore, in today's shipping world, railcar weight is commonly measured at origin and destination points with in-rail track scales. This process is slow and susceptible to false weight measurement.
Weighing devices that use load cells that are on-board railcars are known. For example, U.S. Pat. No. 6,441,324 to Stimpson discloses a weighing system for railroad cars where a load cell is designed to fit on the bottom of the railcar center plate and fit into the railcar truck center bowl. The output of the load cell is provided to a telemetry transmitter, which transmits an indication of weight to a user. While the vast majority of a railcar weight is located above and through the center plate, all railcars experience some sideways rock and roll due to rail track curvature, banking and other irregularities. As a result, the railcar rocks, or pivots, on the center plate. The amount of rock and roll a railcar exhibits is controlled by the side bearings. Under most conditions, moving or stationary, a railcar will be leaning to one side and on one of these side bearings. This causes a weighing system based solely on the center plate, as is the case for the '324 patent, to be inaccurate on many occasions.
A need therefore exists for a weighing system that is accurate, durable and that may transmit data to a remote location.